Tehreek-e-Taliban Pakistan militants carried out the horrendous attack in Pakistan`s northwestern city of Peshawar Tuesday.

"The Taliban have sunk to an all-time depth with this attack," Xinhua quoted Zeid as saying in a statement.

"Everyone must now unite to combat this type of savage extremism." he said.

"No government or intelligence agencies, no religious figures, no wealthy sponsors, no members of the general public can possibly justify continuing support for the Taliban, ISIL (now known as IS or Islamic State), Boko Haram, Al Qaeda or any of these takfiri groups which appear to be competing to attain the highest level of human barbarity," he added.

Al Hussein called for unity to counter such extremism and violence, not only in Pakistan, but anywhere where children`s rights and human rights are attacked in this way.